Peter Gay once mentioned that “there are moments in intellectual history when a small change in quantity induces a change in quality, when the addition of a new shade to a seemingly continuous spectrum produces a new color”. (1) In the history of Christian thought one such moment happened in the eighteenth century, and what took place was enough to make the century of the Enlightenment the great divide between traditional and modern thought about God and theology.

In the eighteenth century decisive changes took place in the course of the development of Christian thought, the results of which are still being felt in the present. These changes were not abrupt; they ere more like end results of long processes of development, and could not have taken place apart from the long developments which preceded them. Yet, that does not take anything away from their great significance. During the eighteenth century these processes were brought to completion, becoming consolidated in views which could only appear in the way they did when the processes were ripe and mature.

The main figure to provide the divide between traditional and modernity in the thought about God and theology was, in my view, David Hume. And the main issue, the great divider, was an epistemological one. The most fundamental question discussed was the problem which was then viewed as the problem of the sources of theology, but which today should be described as the problem of the validation of theological claims. How are theological claims validated, or legitimized? This was the main issue in the eighteenth century – and, in my opinion, is still the main issue – separating believers and skeptics, and, within the class of believers, separating those who did – and do – theology in a traditional form and those who tried – and try – to answer the challenges of modernity.

There may be those who will disagree with my contention that the crisis of modernity was basically epistemological, and hence fundamentally intellectual. Given the limited scope of this paper, it will that one fundamental ingredient in the conflict between tradition and modernity in theology was intellectual – epistemological, to be more precise and specific.

It is unnecessary to document the claim that most theologians, in the history of Christian thought, did feel the necessity of dealing, in one way or the other, with the issue of the sources of legitimization of their theological claims. The problem is fundamental to any theology, since until it is dealt with a theological system, no matter how coherently built, will, so to speak, be floating in the air, without anchorage. It is the responsibility of the theologian to elucidate how his theological claims are to be validated.

Prior to the eighteenth century, theological claims were thought to be validated either by an appeal to reason or by an appeal to some form of revelation. There were theologians who privileged one, or the But most theologians did try to establish the legitimacy of their theological claims through an appeal to either their rationality (or reasonableness) or revealed-ness, or by trying to show that these claims could de deduced or derived from truths which were either rational or revealed. Some went even further and tried to establish the claim that acceptance of revelations was itself rational or reasonable, and that, therefore, even those assertions derived from revelation were, in the last resort also rational or reasonable.

Although the relation between reason and revelation can be expressed in a variety of ways, two such ways have predominated within the history of Christian thought. As Etienne Gilson has pointer out, the various Christian thinkers can be divided into two “spiritual families”:

“The first of those spiritual families … was made up of those theologians according to whom Revelation had been given to men as a substitute for all other knowledge, including science, ethics and metaphysics. Ever since the very origin of Christianity up to our own days, there have always been such extremists in theology” (2).

Some of the representatives of this family have appealed, among other things, to some sayings of St. Paul, as, for instance: “For seeing that in the wisdom of God the world by wisdom knew not God, it pleased God, by the foolishness of our preaching, to save them that believe…

The foolishness of God is wiser than men” (3) When this tradition is mentioned, the name of Tertullian soon occurs to one’s mind. His eloquent words have become famous:

“What indeed has Athens to do with Jerusalem? What concord is there between the Academy and the Church? What between heretics and Christians? Our instruction comes from the porch of Solomon (acts 3:5) who had himself taught that the Lord should be sought en simplicity of hear (Wisd. 1:1). Away with all attempts to produce a mottled Christianity of Stoic, Platonic and dialectic composition! We want no curious disputation after possessing Jesus Christ, no inquisition after enjoying the Gospel! With our faith, that there is nothing which we ought to believe besides (4).

This tradition remained alive throughout the Middle Ages (5) and it has stayed strong even in our own days (6). Karl Barth could be mentioned as one of its main spokesmen in the twentieth century. Gilson lets his own views shine through as he refers to this movement in the Middle Ages: “Had the Middle Ages produced men of this type only, the period would fully deserve the title of Dark Ages which it is commonly given” (7).

But there is another group of thinkers, who, despite various differences, can be grouped together in virtue of their distinctive attitude to the question of reason and revelation. Gilson once more does not hide his sympathies when he describes this second family of thinkers:

“Fortunately, the history of Christian thought attests the existence of another spiritual family, much more enlightened than the first one, and whose untiring efforts to blend religious faith with rational speculations have achieved really important results” (8).

The people included in this spiritual family differ from on another, sometimes very radically, in a number of points. The characteristic which brings them together, however, is their belief that reason and revelation are compatible and harmonious. Some of these thinkers gave undisputed primacy to revelation in this relation. First and foremost here is Augustine (9). Others placed reason and revelation side by side, even though they may have regarded the contents of revelation as more important than the knowledge attained by “unaided” reason. Revelation, although it goes beyond reason, is never contrary to reason, according to these thinkers. The outlook of this group is rather adequately summarized by Richard Hooker, although some of the representatives of the group may not have wished to say it so explicitly:

“The whole drift of the Scripture of God, what is it but only to teach theology? Theology, what is it but the science of things divine? What science can be attained unto without the help of natural discourses and reason? ‘Judge you that which I speak’, saith the Apostle. In vain it were to speak anything of God but that by Reason men are able somewhat to judge of that they hear, and by discourse to discern how consonant it is to truth Scripture indeed teacheth things above Nature, things above Nature, things which our Reason by itself could not reach unto. Yet those things also we believe knowing by Reason that Scripture is the Word of God” (10).

This was written in the sixteenth century. This tradition is much older than this, however. It has been claimed that the Paul of the first chapter of Romans is the father of this tradition. Be this as it may, the Alexandrian Fathers, as the Greek Apologists before them, have an undisputed place within this tradition (11).

Although many theologians advocated a synthesis of reason and revelation before the thirteenth century, it was never very clear, however, what the exact nature of the relationship between the two was. It was also left unclear which items were attainable by human reason, unaided revelation, and which items surpassed the power of this reason. So, although reason and revelation were often brought together prior to the thirteenth century, it was reserved for Thomas Aquinas tackle the problem of the exact nature of the relationship between these sources of legitimization of theological claims, and to clarify the limits of the knowledge provided through an appeal to each of these sources. The historical significance of Thomas’ thought is due, to a large extent, to the fact that he was the first one to get to the roots of the problem, clarifying it and offering a statement of the issues which became classic (12). It was because of this that he consolidated and brought to completion a process which had been developing for some time.

In systematizing the basic theological question, Thomas brought into a coherent whole claims which had often been left loose in the past. Before his time it was never quite clear the exact nature of the relationship between reason and revelation. He clarified this, to his satisfaction, and also made clear, in addition, which theological doctrines he thought could be proved or defended by alone and which could not. By dealing with this whole set of problems in an analytic, but also in a rather systematic fashion, Thomas became the first theologian/philosopher to really go to the roots of the problem of the validation of theological claims. In many ways several of his formulations were not novel at all. What was new was the care with which the problem was dealt, the analytic and systematic fashion in which it was approached, not to say anything about the deep awareness of the paramount importance of the issue.

Despite initial suspicion and attack – which, however, were directed in many cases only to his use of Aristotelian philosophy in his de facto synthesis of reason and revelation – Thomas’ statement of the issue soon became classic. After it was presented, even people who disagreed with the way the question had been put, and/or with the answer given, felt they had to deal with the problem, and offer their own solution.

The late Middle Ages has, as a matter of fact, been described by many as the period in which the great Thomist synthesis was dissolved (13). To a great extent this description is quite correct. The dissolution took place gradually, and as a result of movements within and outside the theological tradition. In the philosophical tradition, the Latin Averroists did their share to bring about the divorce between reason and revelation, using in their attack of the synthesis the famous doctrine of “double truth” (14). Within the theological tradition, Duns Scotus considerably increased the list of those revealed truths which a Christian should believe but could not prove (15). In William of Ockham we find a strange, even if understandable, marriage of philosophical skepticism and theological fideism. He maintained that absolutely nothing could be proved about God in the light of natural reason, not even his existence. Through his work reason and revelation reached divorce (16).

During the Renaissance, we have the thinkers of Northern Italy, with their characteristic neo-Platonic views: Marsilio Ficino an Pico della Mirandola are the most important representatives of this group. But we also have the Northern Humanists, such as Erasmus. Thomas More, John Colet and others. In their own way both of these groups tried to effect a synthesis of reason and revelation again. The syntheses which resulted, however, were rather different from the Thomist one, and very different from one another also (17).

The Protestant Reformation did not introduce significant new elements in the discussion of this issue. Basically, Luther and Calvin, as well as some other representatives of the Reformation, fit into what Gilson has designated as the first family of thinkers, i. e. , those who do not regard religion as a rational enterprise, but as one which is in some respects supra-rational and in some respects downright counter-rational or irrational. To the extent that other figures of the Protestant Reformation leaned toward the acceptance of a natural, or rational theology, they simply came closer to either Thomas’ or the Renaissance models. The Reformers directed their attention mostly to other problems, which are of secondary importance when one views the theological enterprise from the standpoint of its possibility (18).

After the Reformation we have several tendencies. On the one hand, we have John Locke, re-establishing the great synthesis between reason and revelation, even though on grounds different from those used by Thomas or the Renaissance Humanists (19). On the other hand , we have those who did not accept the synthesis – Locke’s or any other – and who argued for the existence of a divorce between reason and revelation. On this side, we have two groups: one group preferred to stay with one partner, the second group with the other. The Deists stuck with reason, with natural religion, and deplored the superstitious belief in miracles and revelation. Here we have John Toland, Anthony Collins, Thomas Woolston, Matthew Tindal, all in Britain. In the Continent we cannot fail to mention Lessing and Voltaire (20). In the opposing camp, we have the Fideists, who denied the possibility of natural theology and argued that faith (even blind faith) was the only avenue of access to religion. Pierre Bayle is the most important representative of this point of view, before the half of the eighteenth century. Even though many commentators doubt his sincerity, Pierre Bayle claimed to be “a Protestant in the full sense of the term” (21), and argued that faith – and if it is non-rational, it ought not to be rationally defensible (22). A rational faith, for him, is a contradiction in terms – the certitude of faith has no other foundation than the fact that one believes it (23).

Up to the time of Hume, therefore, the synthesis between reason and revelation had been constructed, destroyed, reconstructed, destroyed again. But the important thing about this historical development is the following: even those who destroyed the synthesis, such as William of Ockham in the late Middle Ages, the Reformers, the Deists, the Fideists (with the possible exception of Pierre Bayle), did not doubt the possibility of the theological enterprise. They broke up the marriage between reason and revelation, but they were convinced that theological claims could be validated – either through reason (the Deists) or by an appeal to revelation (Ockham, the Reformers, the Fideists). Even a few years before Hume’s time, Locke still defended the synthesis, arguing for “The Reasonableness of Christianity”, trying to show that even the acceptance of revelation was rational, since revelation had been accompanied by miracles which proved its authenticity – hence the importance of the question of miracles in the eighteenth century . Because of this, Christianity, according to him, even in those aspects which cannot be demonstrated by reason, is fully reasonable.

So, up to Hume’s day, either reason or revelation, or both, were thought to be the means of validation of theological claims, and hence the sources of legitimization of the theological enterprise.

Hume’s critique of the theological enterprise was devastating because it went to the grounds of its legitimization – to both of these grounds. This is not the place to discuss Hume’s critique in detail (24).

A brief mention of his main arguments will have to suffice.

Hume attacked revelation, by offering an argument against the credibility of miracles, which were believed to be the guarantee of revelation;

he then attacked reason as a ground of validation of theological claims by criticizing the various arguments which had been offered in attempts to prove the existence of God;

then, in his discussion of the problem of evil, Hume presented a positive argument against the existence of the traditional Christian God, that is, against the existence of an omnipotent, omniscient, and omnibenevolent being (here, instead of merely criticizing arguments for the existence of God, he presented an argument against it);

finally, he gave an answer to the question which naturally comes to most minds, once they discover, or are told, that belief in God and in the main tenets of religion and theology is without rational justification: how are we then to explain the fact that most people believe in God and are, in many ways, religious? In answering this question, in The Natural History of Religion, Hume gave a fully naturalistic account of religion, explaining it in terms of ignorance and of our sentiments of fear and hope.

So, although Hume did not pack all of his remarks on religion and theology neatly together, his critique of religion and theology was as complete and systematic, in the context of eighteenth-century thought, as anyone might wish (or fear). He went to the roots of the theological enterprise, and attacked the pillars on which it was built, in a merciless and thorough fashion. He did not spend his time attacking many secondary aspects of religion or non-fundamental tenets of theology: he inveighed against theology at its most basic, when he launched his attack against both reason and revelation as sources of validation of theological claims.

To the best of my knowledge, Hume was the first major intellectual figure in modern times to launch such a systematic, complete attack upon religion and theology (25). His critique was not a mere compilation of arguments already offered by other people before him – although it did include such. At many specific points his criticism was quite original and novel, and many particular arguments first brought up by him are repeated by contemporary skeptics without much change or alteration (26). The originality an novelty of many of his criticisms, and the fact that he was the first major intellectual figure in modern times to generate such a powerful critique of religion and theology, substantiate, in my view, Richard H. Popkin’s contention that “Hume… is, perhaps, the most important philosophical critic of religious thought in modern times, and the one who presented the most destructive criticism of religious thought” (27).

Hume’s significance for the history of Christian thought depends, to great extent, upon this fact. Never before in the history of Christianity, had the distinctive claims of Christian theology been subjected to such critique as we find is Hume.

The Deists, before Hume, were important in that they rejected revelation as an independent source of theological insight – something not many people had done before them. In so doing they produced a theology which no longer was specifically Christian, despite the many traces of Christian influence it contained. The Deists, however, were still confident that their theological claims could be validated by reason. Their trust in reason, in this regard, was only matched by their distrust of anything resembling revelation.

By accepting the possibility of natural theology, the Deists never doubted the possibility of the theological enterprise as such. They rejected only one of the grounds of validation of theological claims. Although they rejected, in the process, that ground of validation which gave legitimacy to the distinctively Christian elements in the theological tradition, their criticism of theology was not radical. It was left to Hume to launch the radical attack. He concurred with the Deists in their criticism of revelation. Christian apologists had, from the beginning, appealed to miracles as the guarantee of the genuineness and veracity of the Christian revelation. Hume showed that no “system of religion” could be built on such a foundation. But he then went on and offered a devastating criticism of what had been regarded as common ground by most Christian theologians and the Deists: natural theology. In The Natural History of Religion, furthermore, Hume tried to destroy one of the main assumptions of the Deists, namely, the assumption that mankind at first had had a pure natural religion, which consisted of belief in one supreme Being and the observance of the moral law laid down by him. Hume showed that mankind most probably went through a polytheistic stage, before it came to believe in only one God. He showed further that most people believe in God, or in gods, not no the strength of allegedly rational arguments, but for the superstitious reasons.

So, Hume was the first major intellectual figure in modern times to attack and rejected, in a systematic and thorough fashion, both sources of validation of theological claims, reason and revelation. What was aftermath of his attack?

Since prior to Hume’s time reason and revelation were regarded as the only sources of legitimation for theological claims, there were only two intellectually reputable alternatives for those who accepted his critique as valid: one would have either to reject the theological enterprise as altogether groundless or to find a new ground on which to justify theological claims. Hume chose the first alternative. Kant, who endorsed most of Hume’s criticism of natural theology, and who also rejected revelation as such, chose the second alternative. After his own critique of natural theology in the Critique of Pure Reason – a critique partly based on Hume – Kant observes:

“Now I maintain all attempts to employ reason in theology in any merely speculative manner are altogether fruitless and by their very nature null and void, and that the principles of its employment in the study of nature do not lead to any theology whatsoever. Consequently, the only theology of reason which is possible is that which is based upon moral laws or seeks guidance from them” (28) .

Kant hoped that by relating belief in God to moral experience he could show that belief to be rational, thereby bringing (his kind of) religion back to the fold of rationality . Kant’s emphasis on morality was to become very influential upon the nineteenth-century Liberal Theologians. Other people tried to find other solutions to the dilemma: some emphasized religious experience, others emphasized the religious dimension of (secular) experience. Interesting as these suggestions may be, it is beyond the pale of this paper to discuss them. The point of mentioning them is that they were attempts at avoiding the conclusion that theology was groundless, and therefore to be rejected.

I said above that for those who accepted Hume’s conclusions there were only two intellectually reputable alternatives: either to reject the theological enterprise or to find new grounds for it . If one eliminates the underlined words, there will still be another alternative: to claim that religion is to be accepted on the basis of blind faith. There had been people who had rejoiced in religion’s irrationality since the beginning of the history of Christianity; some of the Protestant Reformers did just that, and Pierre Bayle claimed, as we saw, that only by believing the irrational could faith really maintain its identify as faith. Unpalatable as this suggestions may seem to many, specially to eighteenth-century people who had been hearing about the reasonableness of Christianity for over a century, there were those eagerly embraced this alternative. J. G. Hamann did so, and even hailed Hume as the patron saint of his irrational fideism. But Sören Kierkegaard, in the nineteenth century, is, perhaps, the most important representative of this trend.

Of course, it was always possible to deny that Hume’s criticisms were valid and to go on doing theology as before. Roman Catholic theologians, by large, did just that. In the nineteenth century Thoma’s theology was made official Roman Catholic theology for all practical purposes. Various Protestant theologians, however, did the same thing, either by trying to refute Hume, or, more often, by simply pretending to ignore him.

On the whole, however, one can say that most of the creative and original work, in post-Humean times, was done by those who concurred with many of Hume’s criticisms, but wanted to make theology an intellectually respectable discipline, and who had, therefore, to devise a new way of doing theology. Those who tried to refute his views on religion and theology limited themselves, in most cases, to restating arguments which his criticism had already seriously undermined. The success of irrationalist Fideism in the first part of the twentieth century is another indication of how thoroughly Hume did his job.

By attacking what had been considered the only sources of legitimization for theological claims, Hume posed a tremendous challenge to theology. After Hume, theology, if it was to remain a serious intellectual discipline, with some claim to rational status, had to deal with Hume’s critique.

In great part because of Hume, the eighteenth century represents a turning point in the history of Christian thought, being one of those moments in history when, as Peter Gay put it, in the quotation found in the beginning of this paper, “a small addition in quantity induces a change in quality , when the addition of a new shade to a seemingly continuous spectrum produces a new color”. Because of this, therein lies the great divide between tradition and modernity, between traditional and modern thought about God and religion.

11. I do not regard those thinkers who give undisputed primacy to reason as members of this group. Whenever reason is given primacy, it is established as a criterion and it only accepts that which conforms to its own teachings. It ends up, therefore, being the only source of legitimization for theology. When members of this group say, with Hooker, that they know by reason that Scripture is the Word of God they do not mean that if every passage of Scripture is rationally scrutinized it will be concluded that the whole of Scripture consists of passages which could have been discovered by unaided reason. What is meant is, rather, that there are some external evidences, such as miracles, which constitute sufficient ground for any rational person to accept Scripture as the Word of God. This is clearly the case in the work of Thomas Aquinas, and also of John Locke.

12. Cp. Gilson, op. cit. in note 2, pp. 69 ff.

13. Among the many who have spoken of “the dissolution of the Medieval Synthesis” we have John Dillenberger and Claude Welch, Protestant Christianity Interpreted through its Development (New York, 1954), chapter I; cp. F. C. Coplestone, Medieval Philosophy (London, 1952), especially chapters VII to XI

14. Cp. Etienne Gilson, History of Christian Philosophy in the Middle Ages (New York, 1955), pp. 387ff, dealing with the Latin Averroism of Siger of Brabant and Boethius of Sweden, and pp. 521ff, dealing with what Gilson calls “The Second Averroism”, represented by John of Jandun and Marsilius of Padua. According to the doctrine of “double truth”, a thing can be true in philosophy, or according to reason, and yet its opposite could be true in theology, or according to faith.

15. Cp. Gilson, History of Christian Philosophy in the Middle Ages, pp. 454ff.

19. Cp. S. G. Hefelbower, The Relation of John Locke to English Deism (Chicago, 1918) and G. R. Cragg, From Puritanism to the Age of Reason (London, 1950), Richard Ashcraft, “Faith and Reason in Locke’s Philosophy”, in John Locke: Problems and Perspectives, edited by John W. Yolton (Cambridge, 1969)

Cp. 20. John Orr, English Deism: Its Roots and its Fruits (Grand Rapids, 1934), Peter Gay, ed., Deism – An Anthology (Princeton, 1968), and also Gay’s book mentioned in note 1.

24. I have done this in my Ph. D. dissertation, David Hume’s Philosophical Critique of Theology and its Significance for the History of Christian Thought (University of Pittsburgh, 1972)

25. Spinoza may, perhaps, be considered by some as having some precedence. However, his criticism of religion was directed almost exclusively to revelation and the Bible. He did not devote much attention to natural theology as such. Cp. in this context Leo Strauss, Spinoza’s Critique of Religion, trans. by E. M. Sinclair (New York, 1965, originally published in 1930)